Merge tag 'tty-3.15-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull tty/serial fixes from Greg KH:
"Here are some tty and serial driver fixes for things reported
recently"
* tag 'tty-3.15-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
tty: Fix lockless tty buffer race
Revert "tty: Fix race condition between __tty_buffer_request_room and flush_to_ldisc"
drivers/tty/hvc: don't free hvc_console_setup after init
n_tty: Fix n_tty_write crash when echoing in raw mode
tty: serial: 8250_core.c Bug fix for Exar chips.
diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c
index 94f9e3a..0ff7fda 100644
--- a/drivers/tty/hvc/hvc_console.c
+++ b/drivers/tty/hvc/hvc_console.c
@@ -190,7 +190,7 @@
return hvc_driver;
}
-static int __init hvc_console_setup(struct console *co, char *options)
+static int hvc_console_setup(struct console *co, char *options)
{
if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
return -ENODEV;
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 41fe8a0..fe9d129 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -2353,8 +2353,12 @@
if (tty->ops->flush_chars)
tty->ops->flush_chars(tty);
} else {
+ struct n_tty_data *ldata = tty->disc_data;
+
while (nr > 0) {
+ mutex_lock(&ldata->output_lock);
c = tty->ops->write(tty, b, nr);
+ mutex_unlock(&ldata->output_lock);
if (c < 0) {
retval = c;
goto break_out;
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 0e1bf88..2d4bd39 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -555,7 +555,7 @@
*/
if ((p->port.type == PORT_XR17V35X) ||
(p->port.type == PORT_XR17D15X)) {
- serial_out(p, UART_EXAR_SLEEP, 0xff);
+ serial_out(p, UART_EXAR_SLEEP, sleep ? 0xff : 0);
return;
}
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index f1d30f6..cf78d19 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -255,16 +255,15 @@
if (change || left < size) {
/* This is the slow path - looking for new buffers to use */
if ((n = tty_buffer_alloc(port, size)) != NULL) {
- unsigned long iflags;
-
n->flags = flags;
buf->tail = n;
-
- spin_lock_irqsave(&buf->flush_lock, iflags);
b->commit = b->used;
+ /* paired w/ barrier in flush_to_ldisc(); ensures the
+ * latest commit value can be read before the head is
+ * advanced to the next buffer
+ */
+ smp_wmb();
b->next = n;
- spin_unlock_irqrestore(&buf->flush_lock, iflags);
-
} else if (change)
size = 0;
else
@@ -448,27 +447,28 @@
mutex_lock(&buf->lock);
while (1) {
- unsigned long flags;
struct tty_buffer *head = buf->head;
+ struct tty_buffer *next;
int count;
/* Ldisc or user is trying to gain exclusive access */
if (atomic_read(&buf->priority))
break;
- spin_lock_irqsave(&buf->flush_lock, flags);
+ next = head->next;
+ /* paired w/ barrier in __tty_buffer_request_room();
+ * ensures commit value read is not stale if the head
+ * is advancing to the next buffer
+ */
+ smp_rmb();
count = head->commit - head->read;
if (!count) {
- if (head->next == NULL) {
- spin_unlock_irqrestore(&buf->flush_lock, flags);
+ if (next == NULL)
break;
- }
- buf->head = head->next;
- spin_unlock_irqrestore(&buf->flush_lock, flags);
+ buf->head = next;
tty_buffer_free(port, head);
continue;
}
- spin_unlock_irqrestore(&buf->flush_lock, flags);
count = receive_buf(tty, head, count);
if (!count)
@@ -523,7 +523,6 @@
struct tty_bufhead *buf = &port->buf;
mutex_init(&buf->lock);
- spin_lock_init(&buf->flush_lock);
tty_buffer_reset(&buf->sentinel, 0);
buf->head = &buf->sentinel;
buf->tail = &buf->sentinel;
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 036cccd..1c3316a 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -61,7 +61,6 @@
struct tty_buffer *head; /* Queue head */
struct work_struct work;
struct mutex lock;
- spinlock_t flush_lock;
atomic_t priority;
struct tty_buffer sentinel;
struct llist_head free; /* Free queue head */
